Multi-band antenna and design method thereof

Abstract

The present invention provides a multi-band antenna to which the arrangement of Koch fractal antenna is applied. The multi-band antenna is designed in triangular shape whose area is smaller than the general antenna structure. By using the arrangement of Koch fractal antenna, the area of the inverted-F dual-band antenna can be reduced efficiently, so as to enhance more usability.

1. A multi-band antenna, comprising:
 a medium plate having a first surface and a second surface; 
 a ground metal plane located on the second surface of the medium plate; 
 an antenna having a plurality of fractal radiation elements, located on the first surface of the medium plate, wherein each of the fractal radiation elements has an input end and transmits signals with different frequencies, wherein each fractal radiation element is subject to a fractal evolution by winding inwardly for multiple rounds along a geometric locus and gradually narrowing to form a fundamental pattern, and the geometric loci wound by the fractal radiation elements have the same center of gravity and do not overlap; and 
 a signal feed-in module with a plurality of signal feed-in wires corresponding to the fractal radiation elements, and each of the signal feed-in wires connects to the corresponding fractal radiation elements and transmits signals thereto. 
 
   
   
     2. The multi-band antenna of  claim 1 , wherein the fractal evolution comprises N stages of stretching, wherein each stage of the stretching takes place at each straight line section of each fractal radiation element, and the straight line section of the predetermined length is vertically stretched with respect to the straight line section at a central position of each predetermined length, so that a sharp locus protrudes from the predetermined length, wherein N is a positive integer. 
   
   
     3. The multi-band antenna of  claim 2 , wherein the protruding sharp locus is an equilateral triangle locus. 
   
   
     4. The multi-band antenna of  claim 2 , wherein the predetermined length is the length of the straight line section corresponding to one of the fractal radiation elements during the current stage stretching. 
   
   
     5. The multi-band antenna of  claim 1 , wherein the geometric locus is a triangle locus. 
   
   
     6. The multi-band antenna of  claim 1 , wherein the geometric locus is a rectangle locus. 
   
   
     7. The multi-band antenna of  claim 1 , wherein the fractal radiation element is a micro-strip component. 
   
   
     8. A method of designing a multi-band antenna, wherein the multi-band antenna comprises a medium plate, a ground metal plane, an antenna and a signal feed-in module, wherein the medium plate has a first surface and a second surface, the ground metal plane is located on the second surface of the medium-plate, and the antenna has a plurality of fractal radiation elements and the fractal radiation elements are located on the first surface of the medium plate, each of the fractal elements has an input end and transmits signals with different frequencies, and each of the fractal radiation elements is formed by winding a plurality of rounds inwardly around a geometric locus and narrowed gradually to form a fundamental pattern, wherein the geometric loci surrounded by the fractal radiation elements have the same center of gravity and do not overlap, and the signal feed-in module has a plurality of signal feed-in wires corresponding to the fractal radiation elements, and each of the signal feed-in wires connects to the corresponding fractal radiation element and transmits signals thereto, the method of designing multi-hand antenna comprising:
 (a) on each straight line section of each fractal radiation element and an a central position of each predetermined length of interval, stretching the straight line section vertically within the predetermined length with respect to the straight line section, so that a protruding sharp locus is formed on the predetermined length; and 
 (b) repeating the step (a) for N times, wherein N is a positive integer. 
 
   
   
     9. The multi-band antenna design method of  claim 8 , wherein the protruding sharp locus is an equilateral triangle locus. 
   
   
     10. The multi-band antenna design method of  claim 8 , wherein the predetermined length is the length of the straight line section corresponding to one of the fractal radiation elements during the current stage stretching.